Re-add H803 to flake8 ignore list.

I6c2537dd27c947e36ebf37eb3b5c8a1ab8b026a1 mistakenly removed H803 since
running flake8 had no hits for this test, but H803 is the period in the
commit message which we are explicitly ignoring until the next version
of hacking is released (which will remove this check).

Change-Id: I22860cc61336ef5bf8ce4509fe130160bdf7e45b
Merge "Re-add H803 to flake8 ignore list."